Identification of Possible Bonding Sites for Post Deposition Oxygen Absorption in Microcrystalline Silicon

2004 ◽  
Vol 808 ◽  
Author(s):  
L. M. Gedvilas ◽  
A. H. Mahan
Keyword(s):  
Grain Boundaries ◽  
Surface Region ◽  
Oxygen Absorption ◽  
Hot Wire ◽  
X Ray Diffraction ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Crystallite Surface ◽  
Si Films ◽  
Post Deposition

ABSTRACTUsing infrared (IR) spectroscopy and x-ray diffraction, the nature of the grain boundaries in twom c-Si films deposited by hot wire CVD, displaying similar crystalline volume fractionsbut very different behavior upon exposure to atmospheric contaminants, is analyzed. For the film exhibiting significant post deposition oxidation, the IR spectrum in the 2100 cm−1 Si-H stretch mode region contains two sharp and very narrow peaks, suggesting that the crystallites have been incorporated into them c-Si films with their hydrogenated surfaces relatively intact.By comparing these peak frequencies to those in the literature for Si-H bonding on c-Si surfaces, we identify certain crystallite orientations which, when comprising the c-Si grain boundaries, are particularly susceptible to oxidation. We further suggest that the distribution of H in this grain boundary/crystallite surface region is crucial for depositing c-Si films with good electronic properties and minimal post deposition oxidation.

Stress in Hydrogenated Microcrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
D. Peiró ◽  
C. Voz ◽  
J. Bertomeu ◽  
J. Andreu ◽  
E. Martínez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
X Ray Diffraction ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Silicon Thin Films ◽  
Abrupt Changes

AbstractHydrogenated microcrystalline silicon films have been obtained by hot-wire chemical vapor deposition (HWCVD) in a silane and hydrogen mixture at low pressure (<5 × 10-2 mbar). The structure of the samples and the residual stress were characterised by X- ray diffraction (XRD). Raman spectroscopy was used to estimate the volume fraction of the crystalline phase, which is in the range of 86 % to 98%. The stress values range between 150 and -140 MPa. The mechanical properties were studied by nanoindentation. Unlike monocrystalline wafers, there is no evidence of abrupt changes in the force-penetration plot, which have been attributed to a pressure-induced phase transition. The hardness was 12.5 GPa for the best samples, which is close to that obtained for silicon wafers.

Properties of Sputter Deposited ZnO Films Co-doped with Lithium and Phosphorus

2013 ◽  
Vol 1494 ◽  
pp. 77-82
Author(s):  
T. N. Oder ◽  
A. Smith ◽  
M. Freeman ◽  
M. McMaster ◽  
B. Cai ◽  
...  
Keyword(s):  
Rf Magnetron Sputtering ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Hall Effect Measurements ◽  
Sputter Deposited ◽  
P Type ◽  
Post Deposition ◽  
Co Doped

ABSTRACTThin films of ZnO co-doped with lithium and phosphorus were deposited on sapphire substrates by RF magnetron sputtering. The films were sequentially deposited from ultra pure ZnO and Li3PO4 solid targets. Post deposition annealing was carried using a rapid thermal processor in O2 and N2 at temperatures ranging from 500 °C to 1000 °C for 3 min. Analyses performed using low temperature photoluminescence spectroscopy measurements reveal luminescence peaks at 3.359, 3.306, 3.245 eV for the co-doped samples. The x-ray diffraction 2θ-scans for all the films showed a single peak at about 34.4° with full width at half maximum of about 0.17°. Hall Effect measurements revealed conductivities that change from p-type to n-type over time.

Colossal Magnetoresistance in Thick La0.7Ca0.3MnO3 Films

1995 ◽  
Vol 384 ◽  
Author(s):  
Randolph E. Treece ◽  
P. Dorsey ◽  
M. Rubinstein ◽  
J. M. Byers ◽  
J. S. Horwitz ◽  
...  
Keyword(s):  
Colossal Magnetoresistance ◽  
Single Phase ◽  
Laser Deposition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Post Deposition Annealing ◽  
X Ray ◽  
Mr Effect ◽  
Deposited Films ◽  
Post Deposition

ABSTRACTThick films (0.6 and 2.0 μm) of the colossal magnetoresistance (CMR) material, La0.7Ca0.3MnO3 (LCMO), have been grown by pulsed laser deposition (PLD). The films were grown from single-phase LCMO targets in 100 mTorr 02 pressures and the material deposited on (100) LaAlO3 substrates at deposition temperatures of 800°C. The deposited films were characterized by X-ray diffraction (XRD), magnetic field-dependent resistivity, and Rutherford backscattering spectroscopy (RBS). The LCMO films were shown by XRD to adopt an orthorhombic structure. Brief post-deposition annealing led to ~50,000% and ~12,000% MR effect in the 0.6 μm and 2.0 μm films, respectively.

A High-Temperature Study of Phase Precipitation in Superalloys

1959 ◽  
Vol 3 ◽  
pp. 365-375
Author(s):  
John F. Radavich
Keyword(s):  
Heat Treatment ◽  
Electron Diffraction ◽  
Grain Boundaries ◽  
Fluorescence Analysis ◽  
Phase Precipitation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Suitable Heat Treatment ◽  
Nickel Base ◽  
High Temperature Study

AbstractMany of the iron- and nickel-base superalloys exhibit brittle properties on heat treatment, welding, or other fabrication processes at temperatures of about 2000°F or higher. Studies have been carried out by means of electron microscopy, electron diffraction, and X-ray diffraction and fluorescence analysis of the precipitation in the metal and in an isolated form.Results of the electron microscope study of the surface of the metal show a grain boundary constituent to be present which increases in amount as the temperature is increased. Studies on the isolated residue of such samples show a very thin “featherlike” film to be located at the grain boundaries and enclosing the grains. Electron diffraction, X-ray diffraction, and X-ray fluorescence analysis studies of the thin films indicate that they are a TiC phase with very little alloying elements in solution.At temperatures above 2000°F the thin film becomes quite thick and tends to force the grains apart. It is believed that this form of the TiC phase promotes the severe embrittling nature of these alloys at high temperatures. Suitable heat treatment at lower temperatures causes the TiC film to agglomerate and the grain boundaries become “tight,” and a more ductile condition results.

Effect of Sputtering Pressure on the Formation of Semiconducting Mg2Si Films

2010 ◽  
Vol 663-665 ◽  
pp. 166-169
Author(s):  
Qing Quan Xiao ◽  
Quan Xie ◽  
Ke Jie Zhao ◽  
Zhi Qiang Yu
Keyword(s):  
Film Growth ◽  
Diffraction Peak ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Intensity ◽  
Main Diffraction Peak ◽  
Diffraction Peaks ◽  
Si Films ◽  
Sputtering Pressure

Semiconducting Mg2Si films were fabricated on Si (111) substrates by magnetron sputtering and subsequent annealing, and the effects of sputtering pressure on the Mg2Si film growth were studied. The structural and morphological properties of Mg2Si films were investigated by the means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the Mg2Si (220) main diffraction peak intensity increased and then decreased with the increasing of sputtering pressure. The (220) diffraction peak got its maximum at 3.0 Pa sputtering pressure. The intensity of Mg2Si (200) and (400) diffraction peaks increased rapidly as the sputtering pressure decreased when the pressure was lower than 1.5 Pa. The films prepared at higher sputtering pressure had very irregular microstructures, and the surface of semiconducting Mg2Si films became smoother with the decreasing of the sputtering pressure.

Copper(I) Halide Nanoparticle-dispersed Glasses Prepared by Copper Staining

2005 ◽  
Vol 20 (9) ◽  
pp. 2480-2485 ◽  
Author(s):  
Kohei Kadono ◽  
Tatsuya Suetsugu ◽  
Takeshi Ohtani ◽  
Toshihiko Einishi ◽  
Takashi Tarumi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Surface Region ◽  
Borosilicate Glasses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Depth Profiles ◽  
Transmission Electron ◽  
Heat Treated ◽  
Glass Heat

Copper(I) chloride and bromide nanoparticle-dispersed glasses were prepared by means of a conventional copper staining. The staining was performed by the following process: copper stain was applied on the surfaces of Cl−- or Br−-ion-containing borosilicate glasses, and the glasses were heat-treated at 510 °C for various times. Typical exciton bands observed in the absorption spectra of the glasses after the heat treatment indicated that CuCl and CuBr particles were formed in the surface region of the glasses. The average sizes of the CuCl and CuBr particles in the glasses heat-treated for 48 h were estimated at 4.8 and 2.7 nm, respectively. The nanoparticles were also characterized by x-ray diffraction and transmission electron microscopy. Depth profiles of Cu and CuBr concentration in the glass heat-treated for 48 h were measured. Copper decreased in concentration monotonously with depth, reaching up to 60 μm, while the CuBr concentration had a maximum at about 25 μm in depth.

scholarly journals Fabrication of Large-Grain Thick Polycrystalline Silicon Thin Films via Aluminum-Induced Crystallization for Application in Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Hsiao-Yeh Chu ◽  
Min-Hang Weng ◽  
Chen Lin
Keyword(s):  
Solar Cells ◽  
Polycrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Silicon Thin Films ◽  
Si Films ◽  
Two Stages ◽  
Induced Crystallization ◽  
Aluminum Induced Crystallization

The fabrication of large-grain 1.25 μm thick polycrystalline silicon (poly-Si) films via two-stage aluminum-induced crystallization (AIC) for application in thin-film solar cells is reported. The induced 250 nm thick poly-Si film in the first stage is used as the seed layer for the crystallization of a 1 μm thick amorphous silicon (a-Si) film in the second stage. The annealing temperatures in the two stages are both 500°C. The effect of annealing time (15, 30, 60, and 120 minutes) in the second stage on the crystallization of a-Si film is investigated using X-ray diffraction (XRD), scanning electron microscopy, and Raman spectroscopy. XRD and Raman results confirm that the induced poly-Si films are induced by the proposed process.

Photoluminescence of Chemically Etched Polycrystalline and Amorphous Si Thin Films

1993 ◽  
Vol 298 ◽  
Author(s):  
A. J. Steckl ◽  
J. Xu ◽  
H. C. Mogul
Keyword(s):  
Thin Films ◽  
Strong Relationship ◽  
Porous Si ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Si ◽  
Si Films ◽  
Uv Excitation ◽  
Highly Porous ◽  
Stain Etching

AbstractSi thin films were deposited on quartz at temperatures ( TD ) ranging from 540 to 640°C. X-ray diffraction indicates that films deposited at TD < 580°C are amorphous, while those deposited above 600°C are poly-crystalline with a <220> texture. The Si films were made porous by stain-etching in HF:HNO3:H2O. Only Si films deposited at 590°C and above show photoluminescence (PL), centered at ∼650-670 nm under UV excitation. Films deposited at TD < 580°C do not luminesce even after very long etch times, which produce a highly porous structure. The PL intensity and the x-ray signal follow a very similar trend with TD. It appears that a minimum level of crystallinity is required for photoemission in porous Si and that a strong relationship exists between them.

D068 Three-Dimensional X-ray Diffraction Microscopy of Grain Boundaries

2003 ◽  
Vol 18 (2) ◽  
pp. 172-172
Author(s):  
W. Liu ◽  
G. E. Ice ◽  
W. Yang ◽  
J. Z. Tischler ◽  
B. C. Larson
Keyword(s):  
Grain Boundaries ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Microscopy

Microcrystalline Silicon for Solar Cells at High Deposition Rates by Hot Wire Cvd

2002 ◽  
Vol 715 ◽  
Author(s):  
R. E. I. Schropp ◽  
Y. Xu ◽  
E. Iwaniczko ◽  
G. A. Zaharias ◽  
A. H. Mahan
Keyword(s):  
Solar Cells ◽  
Substrate Temperature ◽  
Volume Fraction ◽  
Silicon Layer ◽  
Hot Wire ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Deposition Rates ◽  
Deposition Parameters ◽  
Si Films

AbstractWe have explored which deposition parameters in Hot Wire CVD have the largest impact on the quality of microcrystalline silicon (μc-Si) made at deposition rates (Rd) < 10 Å/s for use in thin film solar cells. Among all parameters, the filament temperature (Tfil) appears to be crucial for making device quality films. Using two filaments and a filament-substrate spacing of 3.2 cm, μc-Si films, using seed layers, can be deposited at high Tfil (∼2000°C) with a crystalline volume fraction < 70-80 % at Rd's < 30 Å/s. Although the photoresponse of these layers is high (< 100), they appear not to be suitable for incorporation into solar cells, due to their porous nature. n-i-p cells fabricated on stainless steel with these i-layers suffer from large resistive effects or barriers, most likely due to the oxidation of interconnected pores in the silicon layer. The porosity is evident from FTIR measurements showing a large oxygen concentration at ∼1050 cm-1, and is correlated with the 2100 cm-1 signature of most of the Si-H stretching bonds. Using a Tfil of 1750°C, however, the films are more compact, as seen from the absence of the 2100 cm-1 SiH mode and the disappearance of the FTIR Si-O signal, while the high crystalline volume fraction (< 70-80 %) is maintained. Using this Tfil and a substrate temperature of 400°C, we obtain an efficiency of 4.9 % for cells with a Ag/ZnO back reflector, with an i-layer thickness of only ∼0.7 μm. High values for the quantum efficiency extend to very long wavelengths, with values of 33 % at 800 nm and 15 % at 900 nm, which are unequalled by a-SiGe:H alloys. Further, by varying the substrate temperature to enable deposition near the microcrystalline to amorphous transition (‘edge’) and incorporating variations in H2 dilution during deposition of the bulk, efficiencies of 6.0 % have been obtained. The Rd's of these i-layers are 8-10 Å/s, and are the highest to date obtained with HWCVD for microcrystalline layers used in cells with efficiencies of ∼6 %.

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